Two groups of rats were either infected with viable E. coli K13 or immunized with formalin killed E. coli K13 by intragastric immunization. Half the rats in each group were subsequently immunized subcutaneously with K13 polysaccharide-BSA conjugate and the antibody response in serum and saliva determined. Intragastric immunization followed by parenteral boosting appears to be a successful means for reproducibly stimulating a local salivary immune response.